Electrical distant-control system



Aug. 24, 1926. C 1,597,416

C. B. MIRICK ELECTRICAL DISTANT CONTROL SYSTEM Filed Sept. 1, 1925 2 h et h e I l \QQQQQQJHIW- l Carlos 5. .Ml rzlck Aug. 24 1926. 1,597,416

C. B. MIRICK ELECTRICAL DISTANT CONTROL SYSTEM Filed Sept. 1 1925 2 Sheets-Sheet 2 Patented Aug. 24, 1,926.

UNITED STATES CARLOS B. MIRICK, OF WASHINGTON, DISTRICT OF COLUMBIA.

ELECTRICAL DISTANT-CONTBOL SYSTEM.

Application filed September 1, 1923. Serial No. 660,596.

My invention relates broadly to distant control systems, and more particularly to a control circuit for a radio transmitter, and a selectively responsive circuit for a radio receiving apparatus whereby particular controls may be caused to function individually or simultaneously.

One of the objects of my invention is to provide a selective control system for radio transmitting apparatus and a selective receiving circuit arrangement whereby particular relay circuits may be operated in accordance with the operation of particular circuits at the radio transmitter.

Another object of my invention is to provide means at a transmitter for controlling particular oscillator circuits independently or a plurality of oscillator circuits simultaneously whereby they cause corresponding circuits at a receiving station to be selectively closed to control particular circuits independently or groups of circuits simultaneously.

Another object of my invention is to provide a control apparatus which ma be connected to a radio transmitter to mo ulate the output of the transmitter at a selected frequency of a range of frequencies, or to modulate the transmitter with a complex wave resulting from a combination of more than one frequency, and means at the receiving station for selectively closing particular circuits -or a plurality of circuits up on the receipt of modulated 'energy from the transmitting station.

Other and further objects of my invention will be understood from the following specification by reference to the accompanying drawings, in which Figure 1 represents diagrammatically the arrangement of the control apparatus at the radio transmitting station; Fig. 2 is a diagrammatic representation of the control apparatus at the radio receiving station; and Figs. 3 and 4: are theoretical diagrams explaining the principle of operation of the control circuits of my invention.

In applying the circuits of my invention to a radio transmitter, the usual radiating system 1 connected to a source of carrier wave frequency 2 is provided with and modulated by my control apparatus repre sented at 4. The modulator includes a plurality of microphone oscillators or vibrators 5, 6, 7 and 8 energized by battery 9 and adjusted independently to different frequencies. nected through switching device 10 to the four intermediate transformers 15, 16, 17, and 18. The four oscillators and transformer circuits have been selected merely for purposes of illustration and it will be understood that more or less may be used. If lever 20 is brought in contact with terminal 5 of switch 10, a circuit is closed which permits the output current of oscillator 5 to pass through the primary 15 of transformer 15. The same holds true for any of the other of the oscillators 6, 7, and 8; that is, oscillator 6 may excite the primary of'transformer 16 by movement of lever 20 into connection with contact 6*, or oscillator 7 may be connected with transformer 17 by movement of lever 20 into contact with 7, or transformer 18 may be energized by oscillator 8 by contacting lever 20 with contact 8. The secondaries 15 16 17", and 18 of the intermediate transformers 15,

The output of these vibrators is con-- 16, 17, and 18 are connected in series and supply energy to the primary winding 21 of transformer 22 whose secondary 23 is connected to modulate the output of the continuous wave radio transmitter 2. The lever 26 can make contact with two sectors at once and thus connect simultaneously any oscillator with the adjacent one either side of it, but not with the fourth oscillator. That is, 5 can be connected with 6 and 8 but not with 7; 6 can be connected with 5 and 7 but not with 8, and so on by movement of lever20 in different positions.

My control system is particularly applicable in maneuvering aircraft without a pilot. I construct the switch 10 in the form of a,jo v stick identical with the joy stick provided in aircraft for controlling the machine. An operator at the radio transmitter at a shore station who is an experienced aviator may therefore move the lever 20 in the same-manner in which he is accustomed to operating the joy stick in aircraft and control circuits at a radio receiver, on board an aircraft as will be hereinafter described, which in turn control the operation of the particular functions necessary in the flight of the aircraft such as operating the elevating planes, the rudder, banking the machine or controlling the engine. My control apparatus is not limited to operation with aircraft but is applicable to any circuits or objects which are to be controlled at a distance. 7

The modulated output of the transmitter is radiated from the antenna system 1, and at the receiving end of'the system the signal therefrom is collected by antenna system 24 amplified and rectified by receiver 25 and finally supplied to the input of a relay apparatus represented at 26. The relay 26 includes a master tube 27 and a plurality of tubes 28, 29, 30 and 31 corresponding to the number of control circuits at the transmitter. The tuned resonant relays 32, 33, 34, and 35, are constructed to respond each to a pitch of modulation of the corresponding oscillators 5, 6, 7 and'8 of the transmitter and are series connected in the plate circuit of the master tube 27 supplied by B battery 46. Suitable resonant relays have been described by me in a copending application Serial No. 660,597, filed September 1, 1923.

If modulator 5 is connected to control transmitter 1, relay 32 at the receiving station responds or correspondingly other controls may function to operate particular relays, or if a combination of controls is operated simultaneously at the transmitter a combination of relays may be closed at the receiver. If, for example, oscillators 5 and 6 are connected sin'iultaneously, as explained, by placing switch lever 20 on both 5" and 6 contacts, relays 32 and 33 will function simultaneously with their respective controlled circuits and similarly various combinations may be secured. Each of the resonant relays 32,33, 34, and 35 independently control the input circuit of electron tubes 28, 29. 30 and 31 respectively, the output circuit of each tube containing secondary relays 36, 37, 38 and 39, an arrangement fully disclosed in a copending application Serial No. 660,598, filed September 1, 1923. The filament electrodes of the electron tubes are energized from battery 40. A constant negative potential is maintained on the grid electrodes of the tubes 28, 29, 30, and 31 from battery 41 connected across the input circuit of each of the tubes through resistances 42, 43, 44-, and 45. The independent resonant relays 3-, 34, and 35 are provided with pairs of contacts 47. 48, 49 and 56 which are normally open, but when any particular relay or group of relays become energized these contacts are closed and charge the grids of the respective tubes with positive polarity derived from battery 51, causing a platecurrent to flow in the particular tube and the secondary relay in that plate circuit to be actuated.

Normally when the contacts 47, 48, 49 or 50 are open the grids are charged negatively and accordingly there will be zero plate current in the particular'tube circuit .so that a maximum value of plate current will be obtained upon the closing of the contacts.

The secondary relays are provided with contacts 52, 53, 54, and 55 with connections which lead off to the circuits to be eona0 trolled.

lVhile I have indicated separate batteries for supplying the negative grid bias and the positive charging potential, separate plate batteries for the master tube 27 andseparate platebatteries for the relay tubes 28, 29, 30, and 31, it will be understood that this is represented for the sake of clearness and that common sources of potential may be employed. ous action of relays, two things are essential. One is, that the wave form, of the resultant E. M. F. derived from two oscillators working at the same time must approach that of a wave in which instantaneseparating again the wave into its two 'com- I ponents would not be as effective. This difference has been represented graphically in Figs. 3 and 4, wherein curve 56 represents the correct combination of two waves at different frequencies as in the case of transformers connected in series as represented in Fig. 1, and Fig. 4 shows the incorrect combination of two waves of different. frequencies as with transformers connected in parallel. lVave 56 represents the effect of one modulator upon the transmitcurve 58 is the-resultant combined wave of,'

the two waves 56 and 57 which would be received upon simultaneous operation of the two oscillators. The desired wave form is shown in Fig. 3.

The second point of importance is, that the waves to be combined should be as nearly as possible of pure sine form without harmonics. This condition is approached by using condensers 59, 60, 61, and 62 to tune the circuits electrically to the periods In securing this simultane- 90 Were the secondaries 100 ber of different frequencies, corresponding to the number of functions to be controlled,

and these functions can be controlled either singly or in pairs of two operating simultaneously to-operate the controls at the re ceiver. v

--iVhile I have described my invention in certain specific embodiments, it is to be understood that modifications may be made and that I intend no limitations other than are imposed by the scope of the appended claims.

' What I claim and desire to secure by Letters Patent of the United States is as follows 1. A radio control system comprising in combination a radio transmitter, means for modulating the output of said transmitter at a plurality of different frequencies, means for receiving the transmitted energy, a master electron tube circuit controlled by the received energy, a pluralityofelectron tubes each connected to said master tube through a relay mechanically tunedto one ofsaid modulating frequenceis, and means connected to each of said tubes and actuated thereby for controlling independent circuits.

2. A radio control system comprising in combination a radio transmitter, means for modulating the output of said transmitter at a plurality of different frequencies, means for receiving the transmitted energy, a master electron tube circuit controlled by the received energy, a plurality of electron tubes each connected to said master tube through a relay mechanically and electrically tuned to one of said modulating frequencies and means connected to each of said tubes and controlled thereby for controlling independent circuits.

3. A radio control system comprising in combination means for transmitting a carrier frequency, means for modulating said carrier frequency with a plurality of-difl'erent frequencies independently or in combination, a receiver, an electron tube connect ed to said receiver, a plurality of relays connected to said electron tube each mechanically tuned to one of said modulating frequencies, electron tubes connected to and controlled by said relays, and circuit-controlling devices actuated by said electron tubes.

4. A radio control system comprising in combination a radio transmitter, means for modulating said transmitter at a plurality of different frequencies comprising independent modulating current generators, transformers each having their primary windings connected'to one of said generator-s, means for exciting one or a combination of said transformers, a circuit connecting the secondary windings of said transformers in series and to said radio transmitter, and means for receiving the transmitted energy and controlling separate circuits thereby including relays mechan ically tuned to said modulating frequencies controlling electron tube circuits.

5. A radio control apparatus, comprising in combination a radio transmitter and receiver, means for modulating said transmitter at a plurality of different frequencies or combinations thereof, comprising a plurality of'generators of different frequencies, a series circuit arrangement for impressing said difierent frequencies on said modulating means, a switch having a contact for each of said generators, a switch lever arranged to make connection with any one or a pair of said contacts whereby the output of said generators may be impressed on said modulator either singly or in combination with another generator, and receiving means having a plurality of selector circuits arranged to respond individually or in pairs to said transmitted ener y.

6. A radio control apparatus, comprising in combination a radio transmitter and receiver, means for modulating said transmitter at a plurality of different frequencies or combinations thereof, comprising a plural ity of generators of different frequencies, a series circuit arrangement for impressing said different frequencies on said modulating means, a switch having a contact for each of said generators, a switch lever arranged to make connection with any one or a pair of said contacts whereby the output of said generators may be impressed on said modulator either singly or in combination with another generator, and receiving means having a plurality of relays connected in series, an electron tube havin grid, filament and plate electrodes connecte to each ofisaid relays, means for normally maintaining all of said grid electrodes at negative potential, means for charging said grid electrodes with positive potential upon closing of said relays and a secondary relay connected to each of said plate electrodes and arranged to be closed either individually or in pairs when said grid electrodes are charged positively.

7. In a radio control system, the combination of a transmitter of a radio carrier frequency modulated at different free controlling relays in the plate circuits of said tubes.

8. In a radio control system the combination oi a transmitter of a radio carrier 5 frequency modulated at a plurality of (lifterent frequencies, and a receiver including relays mechanically selectively responsive to said modulating frequencies, an electron tube for each of said relays, sources of exciting potential in the grid circuits of said tubes adapted to be controlled by said relays, and circuit controlling relays in the plate circuits of said tubes. CARLOS B. MIRICK. 

